1. Field of the Invention
This invention relates to a reverse osmosis water treatment system, more particularly, it relates to a reverse osmosis drinking water treatment system with a backwashable precise prefilter unit. This reverse osmosis drinking water treatment system with a backwashable precise prefilter unit includes a super precise filter, a pressure pump, a reverse osmosis membrane (or nano-filtration membrane) assembly, a pressure tank, a post filter, a drinking water dispensing apparatus, and a backwashable precise prefilter unit.
2. Background Information
Reverse osmosis membranes (or nano-filtration membranes) have very fine pores and a very thin size, and therefore, the membranes are easily dirtied by suspended particles in the incoming water, and they are also susceptible to being attacked or destroyed by bacteria and active chlorine. In order to ensure the membrane's usefulness under ordinary conditions for a long working life, it is necessary to pretreat or prefilter the incoming water. Nowadays, in the market, all reverse osmosis drinking water treatment systems include several filtration steps in series, using either medium types or small types of filters. Usually, these prefilters are composed of precise filters with 1-2 grade cotton or polymer fibers and filters with 1-2 grade active carbon, connected in series. Due to the fact that such filters have no backwashable ability, these prefilter systems with traditional designs must be carefully used to maintain their effectiveness. In tap water, sand, rust, and colloid particles etc. are present; all such dirty particles can accumulate on the precise filter core, and finally its water penetration ability gradually decreases, and eventually, these filters will be destroyed. Secondly, the active carbon can be consumed quickly due to the high content of chlorine in water. The surface adsorption can be gradually saturated, and bacteria in the active carbon can easily grow. In this manner, if the prefilter core can not be replaced frequently, the ordinary working process of the reverse osmosis membrane will be directly destroyed, and the useful life thereof greatly shortened. Usually, every half a year, the core of the prefilter should be replaced. If the tap water has high turbidity, or if high amounts of chlorine exist, the filter core replacement period should be shortened. This means that the customers must pay more for maintenance and also will have more trouble during use.